Hydraulic pulsator transmission and control system



2 sheets-sheet i Filed ,July 11; .1944

March 11, 1947. E. c. BOHALL ETAL.

HWYDRAL-IC PULSATOR TRANSMISSION AND CONTROL` SYSTEM March 1l,4 1947. E.c. BOHALI. ET Al.. 2,417,232

HYDRAULIC PULSATOR TRANSMISSION AND CONTROL SYSTEM Filed July 11.y 19442 sheets-sheet 2 +Qlhf M 3 ATTORNEY Patented Mar. 11? 1947 HYDRAULICPULSATOK TRANSMISSION' AND CONTROL SYSTEM.'l

Earle :0. Bohall;V Oklahoma. City, Okla., .,and' Wallace; R., Bohall,7Seatt'le- Wash- ApplicatibnJxlyH, 194% Serial' No: 544,452

3 Claims..

This-invention-relatesgto hydraulic power transmission and control'systems, andithas reference more particularlyfto improvements in thosetypes of systems-oi remote control referred to'i'n-theart as pulsatorsystems,'wherein a piston of? aitr-ansmitter unit is operable inon'e-cylind'erofa closed, hydraulic system, to eii'ect, throughthefvmediacy of the confined hydraulic medium; an instant andcorresponding movement of` ae pistonfirr the cylinder of a receiverunit; generallylocated' remote from` thetransmitr cylinderf'or theactua'- tion oir some device' or mechanism.

To impart abettery understanding of the invention and its purposes, itwill`be=explained that in vsuch power transmission systems as` aboveidentiiied, involving the use of two or more Ahydraulicy cylinders andconnecting pipev lines,

leakage sometimes does, or is aptto occur about the pistons, or invalvesor fittings; and theremay alsobe loss of hydraulicpressuremediumdue to weeping or seepage through the-pores; of.' thematerials used. Also, temperature changeswill cause an. increase. oradecreaseA in hydrostatic pressure in the. system, making the partseither very hard to operate or loose their action. However, itiiszquiteimportantto successfuloperation ofi such systems, aslisfwell knownt'o1those familiar with'V the art, that the 4pressure lines andcylinders be maintained lledkwiththe hydraulic medium atall timesg. andthat no air pockets or vacuumspaces be permitted toexistsincethiszresuits in the transmitter: andA receiverI pistons' of thesystem. becoming loose, out of5synchronism, or out of proper adjustment.

In View' of. the foregoing, itlha'a been the' principall object of.'this invention to provide al means that is applicable to hydraulicpul'sator systems of the character described, Wherebyany deviation fromon exact synchronization of'. pistons in the transmitter andreceiver'units'. that may result from'. weepingv leakage: or temperaturechanges, will be' automatically corrected; thatris, means. wherebysynchronization: of.' parts'V will be automatically maintained..

More specifically stated', the inventionresides in: the provision' in;a: closed hydraulic system,.of a storage' reservoir for an auxiliary`supply of hydraulic,y medium' fromy which any deficiencyV in thesystem1willbe automatically'replacedfandinto whichy reservoir anyoversupplyfthat' may: exi'strin any line, or connection. fromY anyvreason, will-1 be released throughvthe action2, ofc' relief? valves ofnovely arrangement and mode' or operation..

It'. is a'. further; obj ect: of the, present' invention to provide anovelarrangementofvalvesmoon-- (CL. 60.-54i5) nection with the cylindersof theV receiverA unit, wherebyl movement of' the transmitter pistons toeither' extreme of'travel'will eiect the releasel` of any over'supply ofhydraulic medium in one line andthe rep'lenis'hing of any deiiciency inthe-other required" for re-establisl'lingrv synchronism of' thetransmitterand receiver units.

Still further objects of theinvention reside in the detailsY ofconstruction ofparts, in` their combination, and in their mode ofoperation, as will hereinafter be fully described.

In accomplishing these andy other objects of theinvention,wehavefprovid'ed the improved. details of construction, the preferredforms: of which are illustrated in the accompanying drawings. wherein-Fig.v 1l isaview-illustrating theessential parts of hydrauliccontrolsystem embodying improvements of the present invention; the cylinderhousingfof the transmitter unit and part ofthe housing ofthe receiveruniti being shown in cross section for better understanding of' the.operation.

Fig. 2is a top View ofthe units shown inFig. l,

- partsl being insection forbetter illustration.

3is a cross sectionE on the line 3--3 inv Fig. 2. particularly showingthe valve arrangement, and showing the reservoir for storageofauxiliaryhydraulic' medium;

Fig; 4` isa schematic, sectionaliview, indicating tl'ierelationshipA ofValvey control .cams andl pistons in.: the cylinders of the receiver'unit;

Fig; 5231s' an enlarged; sectional' viewy of one of the'valves and its:actuating cam'.

Referringv more in detai'ltofthe drawings- I-n Figs; l'L andi 2) wehaveillustrated a typical arrangement of parts off a hydraulic controlsystem of4i aI type for which the present inventionk is applicable;v AtoneI end ofthe'system isthe transmitter unit, designated in its entiretyby reference-` character A. andVv atfthe other end offthe systemis thereceiver'unit, designatedinl its` entirety byvreference'characterB';

The transmitter unit comprises a housing l formed;l with two parallelicylinders 2` andv 311 in which respectively; pistons: llv and? 5' arerecipro cally contained; Thepi'stons `are operatively; connected,respectively, by rods orlinks 6 and Twith the oppositeends of a orossarm8-I that` i's keyed orf otherwise Xed'- on al control shaft 9"- which isrotatably mounted inbearings ll'- and I I in oppositesidewalls ofthelhousing l as noted in Fig. 2. Oneendloff this shaft extendsfbeyondthefhousing Wall',.and 'xed thereto aA control l'ever arm', or

handle` i221' whereby: the41 shaft 9 i may be manually rotatably movedto actuate the pistons in their cylinders. The lever arm 8, and theconnecting rods 6 and 1, are so arranged that with the rotatablemovement of the shaft 9, the pistons 4 and 5 will move in oppositedirections in their respective cylinders and in equal amounts.Furthermore it is understood that the cylinders 4 an 5 are equal to eachother in diameter.' Y Thereceiver unit B comprises a cylinder housing2l] that is formed withtwo parallel cylinders 2| and 22, in which,respectively, pistons 23 and]` 24 are reciprocally contained. Thesepistons are operatively connected, respectively, by rods 25 and 2G witha cross arm 28 on shaft 29. Shaft 29 is rotatably supported at its endsin bearings in the opposite side walls of the housing with one endthereof projecting beyond the housing wall and there equipped with alever arm421'to which a link, cable or other device, as seen in Figi. 2,

may be connected for.' the control or actuation of some member.

It is to be understood that the cylinders 2! and 22Vof the receiver unitare alike in diameter and that the cross arm 28 and its pistonconnections are such that the pistons 23 and 24 will move in "with asuitable hydraulic pressure medium which might be oil or alcohol orother suitable liquid Ymedium.

With this arrangement of parts, it will be understood that when the handlever l 2 is actuated, for example, from the full line position shown inFig. 1, to the dotted line position, the hydraulic medium forced fromcylinder 2 through pipe Sii into cylinder 22 will cause upward movementof the piston 24 in the cylinder 22 of the receiver 52 from its lowerend opening into the cylinder 2 I.

The two back check Valves 49 and 50 are normally held closed by springs55 acting thereagainst, and each valve has a vertical stem 56 thereby torotate shaft 29 and cause movement of Y the lever arm 21 from its fullline position in Fig. l to the dotted line, opposite position 21a.Likewise, movement of lever arm l2 from d-o-tted line position to fullline position in Fig. 1, will cause lever arm 21 .to swing from dottedline position 21a to full line position.

As was previously stated, leakage, past piston lwalls, or loss of thehydraulic medium due to seepage or weeping or any changes in volume inlines that mightl be due to temperature changes,

vcauses the parts l2-and 21 to become out of synchronism or normaladjustment, and to Acorrect any departure from synchronism that results,I. vhave provided a novel valve mechanism and controls therefor wherebyhydraulic medium Vmay be either admitted to or released from theconnecceiver unitV comprises a chamberlcontaining an auxiliary supply ofhydraulic pressure medium.

yFormed vertically in the body of the housing 29 at opposite sides ofthe cylinders therein, are ver- .tical channels 42 and 43, each of whichis counterbored at its upper end, which opens into the Ychamber 49, toprovide the valve chambers 44 and 45, to which plugs 46 and41 arefitted. Each plug has a central bore 48 therethrough and in these plugs,back check valves 49 and 59 are seated. In '.Fig. 4, it is shown thatthe channel 42 has a pas- Vsage 5l from its lower end into the lowerend` of cylinder 22 while lthe channel 43 has a passage 21.will berestored to synchronism;

projecting into the chamber 49 beyond the face of the mounting plugwhereby the valve may be depressed to an open position. Y

The plugs v4t and 41 have conical seats 58 against which conical endsurfaces 59 of the valves are engaged to close the valve passages 48.

j Fixed on the cross shaft 29 at opposite sides of the cross arm 28 arecams 60 and 6|. Cam El) is so fixed on shaft 29that it will contact theupper end of stern 56 of valve 49 and depress the valve to open positionas the lever arm 21 reaches the limit of its travel in moving from rightto left as seen in Fig. 1. Likewise, the cam [ill is yso fixed on theshaft 29 Athat it will engage the stem 56 of valve 50 and move the valveto' open position when the lever'arm 21 reaches the final limit Vof itstravel in moving from left to right. When the lever 21 is located at thefull line position of Fig. 1, which is itslirnit of travel in thatdirection, then valve 50 is open and valve 49 is closed. When the lever21 is at its opposite limit, the dotted line position 21a in Fig. 1,then valve 49 is open and valve 50 closed. At any intermediate positionof the lever 2l, both valves 49 and 59 are closed.

l It vhas been found most practical that'the cams be so located thatthey cause opening of their corresponding valves, as the lever 21 movesthrou; h the last four degrees in reaching its limit of travel in eitherdirection. y

, Assuming that the two units A and B have for some reason become out ofsynchronism; for example, assume that when the operating lever arm l2 ofunit A is at the position of eXtreme travel in one direction, indicatedby its full line showing in Fig. l, that the lever 21 has shifted fromits eXtreme position, indicated 'by itsk full line showing, totheupright dash line position 21x. These parts may be restored tosynchronism by moving the lever I2 to its extreme left side position,indicated by the dotted line showing in Fig. A1. With this travel of thelever arm l2 from one eXtreme to the other, the piston'4 is moved Vtoits lower limit, and piston 5 is moved to its upper limit, thusreversing their showing in Fig.

V1. Hydraulic pressure Vmedium is forced' from cylinder 2,'throughV pipeline 30 into cylinder 22. IThis moves the'piston 24 upwardly, andthrough the arm 28 and shaft 29 causes downwardly.

Due to the parts being out of Vsynchronism to the extent'previouslystated, it is apparent that the piston V24A will reach its limits ofupward travel before the piston 4 has reached its lower limit ofmovement.v or piston 5 has reachedits upper limit of travel. l

`This condition will be automatically corrected dueto the fact that astherlever 21 reaches its final travelY toward kthe left,'as shown inFig. 1, the cam 6U that is Xed toshaft 29, contacts the piston 23 tomove Vstem 56 .of valve 49 and depresses the Valve to its open position.This opens the channel 42 for by,-

passing the excess hydraulic medium from the cylinders 2 and 22 andtheir pipe connection,

through channels 5|V and 42 past the open valve and intor the chamberV4l), permitting piston 4 to be moved to its lowerY limit of travelwhile piston 24 is retained at its upper limit of travel.r Piston 5 willthen be atits upper limit of travel and piston 23 at its lower Vlimitand the parts'l2 and In this correcting operation, it is also understoodthat the piston 5 moved to its upper limit of travel after the piston 23had reached its lower limit of travel, and therefore this continuedupward travel of piston 5 that was permitted by reason of the opening ofvalve t9, created suction in pipe line 3 l, and this suction, beingtransmitted to cylinder 2 i, and through passages 52 and 43 to the underside of valve 5t, caused this valve to open and liquid to be drawn fromthe chamber iil to replenish the deciency at this side of the system.Thus, both sides of the system were then completely filled and bothsides restored to correct adjustment and proper synchronism.

It is important in use of this device, that the storage reservoir 49 behigher than the unit A so that the system will be kept filled. If, forany reason, it is not possible or practical for unit B to be placedhigher than unit A, then a standpipe, as indicated at 75 in Fig. 3, canbe connected with the reservoir and extended to a height above the unitA. This standpipe then can be kept lled with the hydraulic medium orconnected with a supply tank.

While we have illustrated check valves of the poppet type, it isunderstood that ball check or other types might be employed withsatisfactory results.

It is to be understood that the present valve arrangement is alsoapplicable to Systems employing single double-ended pistons movable intransmitter cylinders and receiver cylinders arranged after the fashionof those shown in the copending application of R. F. Carr et al., filedAugust 4, 1941, under Serial No. 405,382, now

Patent No. 2,334,383. In such instance, Valve Vequipped connectionswould be made between the storage reservoir and the opposite ends of thecylinder and cams would be arranged on the rotatable, piston-actuatedshaft, to control the valves for the same purpose as herein previouslyexplained.

Having thus described our invention, what We claim as new therein anddesire to secure by Letters Patent is:

1. In a closed hydraulic system of contro1 including a transmittercylinder, a receiver cylinder, a piston in the transmitter cylinder,equipped with means for elfecting positive operating movements thereof,a piston in the receiver cylinder, pressure transmission conduitsconnecting the cylinders whereby positive movements of the transmitterpiston cause corresponding movements of the receiver piston, a containerfor an auxiliary supply of hydraulic pressure medium, channels from saidcontainer for gravity ow of medium to the opposite sides of the pressuresystem, back check valves in said channels arranged to normally sustainmedium in the system against operating pressures, a shaft operable inopposite directions in accordance With travel of the receiver piston inopposite directions, and means on said shaft whereby movement of thereceiver piston to either of its extremes of travel will unseat the backcheck valve at the pressure side of the system for the ejection into theauxiliary supply container of any excess medium then existing in thatside of the system, leaving the valve at the opposite side free to openunder suction for replenishing any deficiency of medium in the oppositeside of the system.

2. In a closed hydraulic system of control, a transmitter unitcomprising paired cylinders, pisf tons operable therein, a rock shaft, across arm on the shaft operatively connected at its ends with thepistons, an actuator lever for the shaft, a receiver unit comprisingpaired cylinders, pistons operable therein, a rock shaft, a cross arm onthe shaft operatively connected at its ends to the pistons, pressureconduits connecting the cylinders of the transmitter unit with those ofthe receiver unit in a manner whereby the rock shaft of the receiverwill be caused to rotate in accordance with rotative adjustment of therock shaft of the transmitter, an auxiliary reservoir in the receiverunit for a hydraulic pressure medium, channels from said reservoir toopposite sides of the hydraulic system, back check valves in saidchannels, cams on the rock shaft of the receiver unit, each for openingone of said valves when the shaft has been actuated to one of itsextreme positions. v

3. In a hydraulic system, a transmitter means, a receiver cylinder, apiston means movable therein between established limits of travel,pressure conduits connecting the opposite sides of the transmitter meanswith opposite sides of the receiver cylinder, a storage reservoir for anauxiliary supply of hydraulic medium, channels from said reservoir tothe opposite sides of the hydraulic system, a back check valve in eachchannel for holding pressure in the system, and a shaft connected withthe piston means for rotation in opposite directions with movement 0fthe piston means in opposite directions, and means actuated by the shaftwith the movement of the piston means to its extremes of travel forunseating the valve in the channel that opens f to that side of thesystem which is, at that time,

the pressure side.

EARLE C. BOHALL. WALLACEl R. BOHALL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS 55 Number Name Date 976,907 Pagendarm Nov. 29,1910 1,213,721 Williamson Jan. 23, 1917 2,243,385 Levy May 27, 19412,330,678 Carlton Sept. 28, 1943 60 FOREIGN PATENTS Number Country Date473,909 British Oct. 22, 1937 500,673 British Feb. 14, 1939

